Vehicles that improve fuel economy by performing idling stop control that improves fuel economy by stopping idling when the vehicle stops traveling at an intersection and so forth and so forth have conventionally been proposed. Further, vehicles in which an engine and a motor are installed as drive sources improve fuel economy by shutting down the engine when the vehicle has stopped traveling.
There are many vehicular heating systems resulting from vehicular air conditioning systems. Heating by a vehicular air conditioning system uses the heat of engine cooling water as a heat source, so in a case where the temperature of the cooling water is low, a desired heating effect cannot be obtained. That is, in vehicles that perform idling stop control such as described above and hybrid automobiles that have a mode in which they shut down the engine and travel by motor during travel, if the temperature of the cooling water ends up dropping, a heating effect ends up becoming unobtainable.
Therefore, hybrid automobiles and so forth are configured in such a way that, on the basis of a threshold value of the temperature of the engine cooling water predetermined in accordance with a target temperature at outlet (TAO) of the vehicular air conditioning system, engine shutdown and engine startup are performed, a drop in the temperature of the cooling water is suppressed, and a heating effect is obtained.
Further, there are vehicle which, in addition to the heating effect resulting from the vehicular air conditioning system, are further equipped with a seat heater separately and obtain a heating effect. In vehicles equipped with such a seat heater, heating by the vehicular air conditioning system and the seat heater is performed in an operating mode (a so-called energy-saving mode) that improves fuel economy by shutting down the engine when the vehicle has stopped traveling. In order to improve fuel economy in an operating mode resulting from this energy-saving mode, in the technology described in JP-A No. 2006-151039, allowing an air conditioner and a seat heater to operate while keeping them below their normal working power when performing heating in the energy-saving mode is proposed. By keeping the air conditioner and the seat heater below their normal working power, they can be allowed to operate while keeping their outputs down in the energy-saving mode than in a normal operating mode, and fuel economy can be improved.